Jet pump slip joint with axial grooves

Abstract

A uniform leakage flow device for the slip point of piping systems, and particularly in reactor pressure vessels, selectively imposes a steady, uniform flow of fluid through the slip joint between two adjacent pipe surfaces to thereby eliminate the detrimental flow-induced vibration associated with the unsteady and non-uniform leakage of fluid through the slip joint field. The uniform leakage flow device comprises a plurality of axial grooves that are formed in the wall surface of the slip joint.

1 . A uniform leakage flow device for a jet pump assembly having an inlet mixer coupled to a diffuser and defining a slip joint therebetween, comprising: a plurality of axial grooves formed in the wall surface of the slip joint defined between an outer wall surface of the inlet mixer and an inner wall surface of the diffuser. 
   
   
       2 . The uniform leakage flow device of  claim 1  wherein said plurality of axial grooves is formed in the outer wall surface of the inlet mixer. 
   
   
       3 . The uniform leakage flow device of  claim 1  wherein said plurality of axial grooves is formed in the inner wall surface of the diffuser. 
   
   
       4 . The uniform leakage flow device of  claim 1  wherein the number, width and depth of each said plurality of axial grooves is defined by the following equations when the axial grooves area is equal to the slip join leakage area, where A is the slip joint leakage area, N is the number of axial grooves, D is the outer diameter of the inlet mixer, w is the width of the axial groove, d is the depth of the axial groove and g is the distance of the radial gap, then:
     A =3.14159 ×D×g=N ×w×d        hence,       w =3.14159 ×D×g /( N×d ).   
   
   
       5 . The uniform leakage flow device of  claim 1  wherein the number of axial grooves formed in said wall surface is at least four. 
   
   
       6 . The uniform leakage flow device of  claim 1  wherein said depth of each said axial groove of said plurality of axial grooves is two to four times the distance of the radial gap of the slip joint, said radial gap being defined as the distance between the outer wall surface of the inlet mixer and the inner wall surface of the diffuser. 
   
   
       7 . A method of forming a uniform leakage flow device in the slip joint of a jet pump assembly having an inlet mixer positionable within a diffuser, comprising: forming a plurality of axial grooves in the wall surface of one of the outer wall surface of
 the inlet mixer or the inner wall surface of the diffuser; and positioning the inlet mixer within the diffuser.   
   
   
       8 . The method of  claim 7  wherein said axial grooves are formed in said outer wall of said inlet mixer. 
   
   
       9 . The method of  claim 7  wherein said axial grooves are formed in said inner wall surface of said diffuser. 
   
   
       10 . The method of  claim 7  wherein said axial grooves are machined in said wall surface underwater.